Three New South American Species of Randia (Rubiaceae, Gardenieae)

Abstract

Three new species of South American Randia (Rubiaceae, Gardenieae) are described and illustrated: Randia wigginsii Standley ex Gustafsson from montane tropical forests in Ecuador and northern Peru is mainly recognized by its tomentose to velutinous corolla tube and the lanate-velutinous pedicels and fruits. The possible features of being unarmed and having single male flowers are discussed. Randia pubistyla Gustafsson from lowland tropical dry forests in western Ecuador and Colombia is recognized by its puberulous style, the tomentose to puberulous fruits that usually are crowned by a calyx with reflexed lobes, and by the small thorns. Randia longifolia Gustafsson from lowland tropical humid forests in western Ecuador is mainly recognized by its relatively large, glabrous corolla, the linear calyx lobes, and by the reticulate finer vasculature on the abaxial surface of the leaves. The affinities for each species are discussed. Randia is a neotropical genus of approximately 90 species ranging from ca. 30'N to 30'S. In South America and the Caribbean there are approximately 45 species. The genus is represented by shrubs, trees, and lianas in deciduous and evergreen vegetation from sea level to about 3300 m elevation. Randia can be recognized from other members of the Gardenieae by the following combination of characters: dioecious (female flowers with nonfunctional stamens, male flowers with a nonfunctional stigma and rudimentary ovary), pollen in permanent tetrads, a unilocular ovary with two parietal placentas, fruits with many discoid seeds embedded in a sweet pulp that turns dark when dry, thorns, and conspicuous short-shoots with clustered stipules and leaves. There are, however, exceptions. Monoecious and hermaphroditic species have been reported (Lorence & Dwyer, 1987; Burger & Taylor, 1993), pollen in dyads or monads have been reported (Burger & Taylor, 1993), some species are unarmed (Burger & Taylor, 1993; pers. obs.), and sometimes the short-shoots are less conspicuous (Burger & Taylor, 1993; pers. obs.). Within the genus there is also variation in the structure of the inflorescence. The inflorescences are usually terminal but sometimes axillary or cauliflorous (Burger & Taylor, 1993). Female flowers are usually solitary but sometimes in fascicles of 2 to 8 flowers (Burger & Taylor, 1993). The male flowers are usually in fascicles with a few to several flowers but sometimes form cymes with many flowers (Lorence & Nee, 1987; Lorence & Dwyer, 1987) and are sometimes solitary. This large variation makes it difficult to understand which genus has the closest affinities to Randia. Robbrecht and Puff (1986) discussed that all genera in Gardenieae with pollen shed in permanent tetrads may represent a natural group. This gained support in a phylogenetic analysis by Persson (1996) but was contradicted by Andreasen and Bremer (1996, in press) and Persson (in press), who discussed that pollen in tetrads may have arisen several times in Gardenieae. In Persson's (1996) analysis Casasia gained support as sister to Randia, but the later mentioned analyses did not point out any strongly supported sister to Randia. Other neotropical genera that in these analyses (Andreasen & Bremer, 1996, in press; Persson, in press) grouped together with Randia and Casasia as possible relatives were Rosenbergiodendron, Sphinctanthus, and Tocoyena. Sphinctanthus and Tocoyena were not included in the analyses by Andreasen and Bremer (1996, in press). In this group the genus with the morphologically nearest affinities to Randia is Casasia by being dioecious and having pollen in tetrads. Lorence (1986) and Lorence and Dwyer (1987) discussed the morphological features in Casasia and Randia and also expressed doubt (Lorence & Dwyer, 1987) whether Casasia can be maintained as a valid genus. More phylogenetic studies in Gardenieae need to be done in order to find the monophyletic group to which Randia belongs. The taxonomical work in Randia is complicated by the intraspecific variation in size and shape of leaves, calyx lobes, degree of pubescence, persistence of stipules and calyx, and number of thorns. NOVON 10: 201-208. 2000. This content downloaded from 157.55.39.78 on Mon, 20 Jun 2016 07:14:24 UTC All use subject to http://about.jstor.org/terms